1. Technical Field of the Invention
The present invention relates generally to semiconductor devices and, more particularly, to a robust, cost effective leadframe structure which includes one or more built-in connectors for cables and is particularly suitable for a concentrated photovoltaic (CPV) receiver module.
2. Description of the Related Art
Photovoltaic cells are a well known means for producing electrical current from electromagnetic radiation. Traditional photovoltaic cells comprise junction diodes fabricated from appropriately doped semiconductor materials. Such devices are typically fabricated as thin, flat wafers with the junction formed parallel to and near one of the flat surfaces. Photovoltaic cells are intended to be illuminated through their so-called “front” surface. Electromagnetic radiation absorbed by the semiconductor produces electron-hole pairs in the semiconductor. These electron-hole pairs may be separated by the electric field of the junction, thereby producing a photocurrent.
There is currently known in the electrical arts semiconductor devices known as CPV receiver die packages or modules. Currently known CPV modules typically comprise a ceramic substrate having a conductive pattern disposed on one side or face thereof. Attached to the substrate and electrically connected to the conductive pattern are electrical components, including a pair of preformed wire connectors and a packaged diode. Also attached to the substrate and electrically connected to the conductive pattern thereof is a receiver die. The electrical connection between the receiver die and the conductive pattern is often facilitated by a pair of punched thin metal foil or braided ribbon/mesh connectors which extend along and are welded or soldered to respective ones of opposed sides of the receiver die, which typically has a quadrangular or square configuration. In certain existing CPV modules, the electrical connection of the receiver die to the conductive pattern is facilitated by the use of multiple wires bonded to the bus bar on the receiver die and the bond pads of the conductive pattern of the substrate, the wires being used as an alternative to the aforementioned braided ribbon or mesh interconnects. The CPV module may further include a light concentration means which is adapted to concentrate solar radiation onto the front surface of the receiver die.
However, one of the major disadvantages associated with currently known CPV modules is attributable to the relatively high cost associated with their assembly and testing. Another deficiency lies with the lower conversion efficiency resulting from the higher receiver die temperatures. These higher temperatures of the receiver die are often attributable to the inefficiencies of known CPV modules in dissipating heat. In order to address these disadvantages, Applicant developed a robust, cost effective leadframe structure for integration into a CPV receiver package, such leadframe structure being described with particularity in Applicant's U.S. patent application Ser. No. 12/348,853 entitled LEADFRAME STRUCTURE FOR CONCENTRATED PHOTOVOLTAIC RECEIVER PACKAGE filed Jan. 5, 2009, the disclosure of which is incorporation herein by reference. Though the leadframe based CPV receiver packages such as those described in U.S. patent application Ser. No. 12/348,853 address and overcome many of the major disadvantages with the ceramic substrate based CPV receiver packages described above, such leadframe based CPV packages still typically require a connection to be attached for permitting cables to be serially coupled between the receiver die of the receiver package. In this regard, current designs of leadframe based CPV receiver packages often include cavities in the mold cap which permit the cables to be either soldered to the leadframe or to a connector attached to the leadframe. The present invention provides a further enhancement to these leadframe based CPV receiver packages by creating the connector(s) for the cables from the core leadframe. As a result, no additional connectors are required, with the cables having a firm attachment to the leadframe. Costly supplemental connectors are thus eliminated, with the leadframe based CPV receiver package including the connectors having improved reliability versus a non-connector solution. In this regard, serious reliability issues arise when attempts are made to solder the cables to a leadframe which has no connectors. These, and other features and advantages of the present invention, will be described in more detail below.